The present invention relates to systems for arresting a patient's heart and maintaining a patient on cardiopulmonary bypass. Such systems are used when performing surgical procedures, such as coronary artery bypass grafting, on an arrested heart.
In conventional open-heart surgery, the patient's breast bone is sawed open, the chest is spread apart, and the heart is accessed through the large opening created in the patient's chest. The patient is placed on cardiopulmonary bypass and the patient's heart is then arrested using catheters and cannulae which are inserted directly into the large arteries and veins attached to the heart through the large opening in the chest. The arterial cannula typically passes through the wall of the ascending aorta and a cross-clamp is applied to the ascending aorta to isolate the coronary arteries from the remainder of the arterial system. A venous cannula passes through the right atrium for withdrawing blood from the patient.
Recent developments in cardiac surgery have enabled surgeons to perform coronary artery bypass grafting and valve repair and replacement procedures without creating a large opening in the patient's chest. These developments have significantly reduced trauma to the patient by eliminating the need for sawing open the breast bone and opening the patient's chest. Such procedures are disclosed in U.S. Pat. Nos. 5,452,733 and 5,571,215 which are hereby incorporated by reference.
In order to perform such surgical procedures, the patient's heart must be arrested and the patient placed on cardiopulmonary bypass without direct access to the heart. Catheters and cannulae for arresting the patient's heart and establishing bypass without requiring direct access to the patient's heart are disclosed in U.S. Pat. Nos. 5,584,803 and 5,558,644 which are hereby incorporated by reference.
The systems described in U.S. Pat. Nos. 5,584,803 and 5,558,644 include an aortic occlusion device which has a balloon to occlude the ascending aorta and a lumen to deliver cardioplegic fluid for arresting the patient's heart. The aortic occlusion device replaces the conventional external cross-clamp and advantageously reduces the amount of displacement and distortion of the aorta. Minimizing distortion of the aorta may reduce the amount of emboli released and, therefore, may reduce stroke incidents.
A venous cannula withdraws blood from the patient and blood is returned to the patient through an arterial cannula which is placed at a peripheral artery such as the femoral artery. In a preferred embodiment, the aortic occlusion device passes through the arterial cannula thereby minimizing the number of penetrations in the patients vascular system.
The systems described in U.S. Pat. Nos. 5,584,803 and 5,558,644 also include an endovascular coronary sinus catheter for retrograde perfusion of a cardioplegic agent, preferably blood cardioplegia, via the coronary sinus. The coronary sinus catheter preferably passes through the internal jugular vein and has an inflatable balloon for occluding the coronary sinus. An endovascular venting catheter extends through the tricuspid and pulmonary valves for venting the pulmonary artery.
Although the endovascular bypass system has performed admirably and has enabled surgeons to perform less invasive cardiac procedures, the extracorporeal bypass circuit which couples the catheters and cannulae to the cardiopulmonary bypass elements may be optimized.
Thus, a specific object of the present invention is to provide an extracorporeal flow circuit for use with endovascular cardiopulmonary bypass systems.